培养大鼠颈上神经节神经元γ-氨基丁酸电流的全细胞记录

WHOLE-CELL RECORDING OF GABA CURRENTS IN CULTURED RAT SUPERIOR CERVICAL GANGLION NEURONS

在培养的大鼠颈上神经节神经元上，用全细胞膜片钳技术记录γ－氨基丁酸（ＧＡＢＡ）所激活的通道电流。当膜电位钳制在－６０ｍＶ时，压力喷射ＧＡＢＡ２０μｍｏｌ／Ｌ引起的峰电流为７３６±４８４ｐＡ（ｎ＝３１）。对ＧＡＢＡ电流与膜电位的关系的分析表明，当膜电位钳制在正负水平时，ＧＡＢＡ分别引起外向及内向电流，但外向电流的斜率稍大于内向电流，即存在轻度外向整流。电流的反转电位接近０ｍＶ。为了确定ＧＡＢＡ受体通道对Ｃｌ－的通透性，观察了改变细胞内Ｃｌ－浓度对ＧＡＢＡ电流的反转电位的影响。结果发现，所测的反转电位与用Ｇｏｏｄｍａｎ—Ｈｏｄｇｋｉｎ—Ｋａｔｚ方程预测的结果相符，提示ＧＡＢＡ受体对Ｃｌ－具有选择通透性，可能属ＧＡＢＡＡ受体。

Responses of cultured rat superior cervical ganglion (SCG) neurons to local application of GABA were studied by using whole-cell voltage-clamp technique. The peak inward currents activated by 20μ mol/ L of GABA were 736± 484 PA (n=31) at a holding potential of -60mV. The GABA currents showed slight outward rectification and reversed at near 0mV in symmetric Cl- solution. To investigate the ion permeablity of the GABA channel, we studied the effect of different intracellular Cl- on reversal potentials of GABA currents. The results showed that the reversal potentials were in accord with values predicated from Goodman-Hodgkin-Katz potential equation. Taken together, our data suggest that G ABA receptor of cultured SCG neurons is most likely of GABAA type.